Various non-destructive testing systems use lasers. By way of example, laser bond inspection systems use lasers to evaluate the bond strength of adhesive bonds in composite structures. To evaluate the bond strength of an adhesive bond within a composite structure, an absorbing overlay and a transparent overlay can be provided on the composite structure. The laser bond inspection system can then cause a laser to emit a pulse that passes through the transparent overlay and is absorbed by the absorbing overlay. The absorption by the absorbing layer exerts pressure on the composite structure, thereby driving a stress wave into the composite structure. The laser bond inspection system can control the strength of the pulse such that the stress wave will cause the adhesive bond to fail if the bond is weak, but will have no effect on the adhesive bond if the adhesive bond is sufficiently strong. If the stress wave causes the adhesive bond to fail, the failure can be detected by a sensor positioned on the surface of the composite structure.
Laser ultrasonic inspection systems also use lasers. More specifically, laser ultrasonic inspection systems use lasers to detect defects, such as delaminations, inclusions, voids, or disbonds, in structures. For example, a laser ultrasonic inspection system can cause a laser to emit pulses that contact a surface of a structure, thereby generating ultrasonic waves. The ultrasonic waves can then interact with features on an interior of the structure, and propagate to the surface of the structure. A detector of the laser ultrasonic inspection system can then measure the ultrasonic waves, and the laser ultrasonic inspection system can analyze the measured ultrasonic waves to determine one or more characteristics of the structure.